The present invention relates to small compressors of the type used to power airbrushes or similar tools, and specifically to an attachment for such a compressor which, among other things, improves the temperature and pressure characteristics of the compressor.
Conventional small compressors of the type used with airbrushes typically are powered by shaded pole motors, as opposed to capacitor start motors used in larger compressors. Small compressors of the type referred to presently may also be defined as having motors producing under 1/2 horsepower. Such compressors are used by commercial artists, photographers, cake decorators, hobbyists and manicurists, among others.
A common operational problem of such compressors, especially when used in an airbrushing environment is that the compressor runs continually. Such continual operation generates excessive heat and vibration. Excessive heat during compressor operation damages airbrush hoses and control devices, and also promotes corrosion at the point the hot air is finally cooled and condenses on various components of the system. Larger compressors often employ elaborate aftercooler devices to lower air temperature where necessary. However, such devices are impractical for use with small compressors. Vibration of the compressor is annoying to the operator, and has also been known to cause the compressor to "walk" across a table or other substrate.
Another drawback of conventional small compressors, especially those incorporating reciprocating pistons, is that the pistons emit the compressed air on a pulsating basis, which tends to vary the pressure received by the airbrush. Such unstable pressure flow interferes with the desired uniform flow needed for optimum airbrush operation, and results in unsatisfactory work product. On larger compressors, a storage tank or reservoir is provided which absorbs the unwanted pulsations. These storage tanks, which typically have a low surface to volume ratio of less than 1:1, are normally unsuitable for use with small compressors.
Yet another drawback of conventional small compressors is that there is no way to easily depressurize the system once the compressor is turned off. Instead, a significant pressure load is held within the system. Once the operator desires to restart the compressor, it is often difficult for the compressor motor to overcome the stored pressure load. Repeated restarts of this nature cause additional wear and tear and shorten the working life of the compressor.
Still another drawback of conventional small compressors is the inability to accurately monitor and control system pressure. Attempts to control the output of small compressors typically involve the insertion of a regulator which controls downstream air pressure only, i.e., the pressure between the regulator and the air tool to which it is connected. Any enclosed upstream volume (hose, piping or reservoir) between the compressor and the regulator receives the maximum output pressure of the compressor at all times, creating significant back pressure. Running constantly, the compressor is always pumping air against a backpressure equal to its maximum output, and works very hard in the process, This results in maximum wear on the compressor and the generation of excess heat and noise. Also, some small compressors are provided with needle-type bleeder to valves which relieve excess pressure. However, such valves are difficult to accurately adjust and often lose their adjustment through compressor vibration. Further, standard dry air pressure gauges cannot be used effectively on small air compressors. Pulsation and vibration generated by the compressor make the needle vibrate so violently as to be virtually unreadable. Gauge life is also extremely short because of the constant shock.
Accordingly, a principal object of the present invention is to provide an improved compressor attachment which dissipates compressor-generated heat before it can be transmitted to the pneumatic tool.
Another object of the present invention is to provide an improved compressor attachment which ameliorates the compressed air output pulses inherent with small compressors, especially the piston type.
Yet another object of the present invention is to provide an improved compressor attachment which provides the operator with precise control over pressure output.
Still another object of the present invention is to provide an improved compressor attachment with features for minimizing stored pressure loading upon shutting off of the compressor.
A still further object of the present invention is to provide an improved compressor attachment with devices for minimizing excessive vibration and the unwanted "walking" of the compressor across the substrate.